Salvinia minima

Salvinia minimaBaker
(Latin: minimus, least or smallest, presumably in comparison with the size of other species)

Local names: common salvinia, water-spangles, least water-spangles, floating fern

Stems 1–6 cm long; floating leaves usually 6–15 mm long, rounded to cordate basally, obtuse or notched apically, usually not folded; 2n = 4x = 36, 2n = 6x = 54 (de la Sota & Cassa de Pazos 2001). Lakes and other aquatic habitats; Jasper (Holmes et al. 10787, BAYLU), Jefferson (Hatch 6403, TAES), Harris, (P. Rolling s.n., SBSC), Robertson (Turner et al. 2003), Orange (L.E. Brown 18756, TAES), Tyler (R. Helton, pers. comm.), Angelina, Sabine, Travis (Morgan 2010), and probably Newton (it is known from the LA side of Toledo Bend—R. Helton, pers. comm.) cos. In East TX and farther w in Wichita Co. in the e Rolling Plains (Morgan 2010); naturalized in scattered localities across se U.S. (AL, AR [Peck 2011a], FL, GA, LA, MS, SC, and TX [Jacono et al. 2001]), also CA (reported 2009 by Riefner & Smith); also Mexico to South America. Sporulating spring and fall (according to Nauman 1993d; however, the spores are apparently functionally sterile and the plants only reproduce vegetatively— Riefner & Smith 2009; Morgan 2010). [S. rotundifolia of authors, not Willd.] In TX it is considered a “harmful or potentially harmful exotic plant,” and it is illegal to release, import, sell, purchase, propagate, or possess this species in the state (Harvey 1998). In certain parts of East TX, populations of this species are so large that recreational access (e.g., boating and hunting) is being impeded (H. Elder, pers. comm.). As is the case with S. molesta, this species is capable of forming thick mats (as thick as 20–25 cm) (Montz 1989; Morgan 2010). In the past S. minima was considered native to the se U.S. (e.g., Nauman 1993d), but is now thought to have been introduced from tropical America where it is native from Mexico s to Argentina (Jacono et al. 2001; Tipping et al. 2009; Morgan 2010). It was first reported in the U.S. from the St. Johns River, Florida in 1928 (Small 1931 as S. auriculata; Tipping et al. 2009). It was probably introduced into FL in the 1920s, and “the plant may have entered natural areas through flooding of water-gardens and ornamental ponds” (Jacono et al. 2001). It was introduced into TX in 1992, apparently from w LA “on a ‘marsh buggy,’ during geologic exploration” (Jacono et al. 2001; see also Hatch 1995). The spread of this species is apparently limited by a “low tolerance to freezing temperatures and saline waters” (Riefner & Smith 2009).

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